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All Models (1973)

  1. Turn mixture screws in (clockwise) until screws lightly contact seat, then back out (counterclockwise) each screw four full turns.
  2. Adjust idle stop solenoid or idle speed screw to achieve specified initial idle RPM, then adjust mixture screws in (clockwise) equally to obtain final idle RPM.
  3. When idle mixture setting is specified as 1/4 turn from lean roll, turn mixture screws equally in (clockwise) to a 20 RPM drop, then back out (counterclockwise) 1/4 turn.
  4. Install new idle limiter caps, and reconnect distributor vacuum advance hose and fuel tank vapor canister hose (if Corvette, replace gas cap).
Preliminary Idle Speed Specifications

Application Initial Idle RPM Final Idle RPM
140"
  Auto. Trans. 800 (1)750
Man. Trans. 800 (1)700
250"
  Auto. Trans. 630 600
Man. Trans. 750 700
307"
  Auto. Trans. 630 600
Man. Trans. 950 900
350" 2-Bbl.
  Auto. Trans. 630 600
Man. Trans. 1000 900
350" 4-Bbl. (2)
  Auto. Trans. 620 600
Man. Trans. 920 900
350" 4-Bbl. High Performance (2)
  Auto. Trans. 720 700
400"
  Auto. Trans. 630 600
454"
  Auto. Trans. 625 600
Man. Trans. 925 900
(1) GT option with air conditioner, set @ 800 RPM.
(2) Set mixture 1/4 turn from lean roll.